Hammer operated switch construction

ABSTRACT

A switch construction including a base with at least a pair of stationary contacts on the base and at least one movable contact pivotally mounted on the base for movement relative to the stationary contacts. A hammer is provided for engaging the movable contact to achieve the movement of the movable contact. This hammer includes a first portion engaging the movable contact on one side or the other of the pivot axis of the movable contact. The hammer includes striking portions on opposite sides of the first portion with the striking portions alternately engaging oppositely extending sections of the movable contact. A ridge is defined at the pivot axis of the movable contact, and the first portion of the hammer is initially forced against this ridge during switch actuation and thereafter the first portion moves rapidly over the ridge at the same time as a striking portion of the hammer engages the movable contact.

ilnited States Patent 11 1 1111 3,746,809

Gaber July 17, 1973 HAMMER OPERATED SWITCH Primary Examiner-David Smith, Jr.

CONSTRUCTION Attorney-McDougall, Hersh & Scott [76] Inventor: wiilllglgttgagil', 2301 Greenwood, ABSTRACT A switch construction including a base with at least a [22] Fled: 1972 pair of stationary contacts on the base and at least one 1 APPL 22 0 7 movable contact pivotally mounted on the base for movement relative to the stationary contacts. A hammer is provided for engaging the movable contact to [52] U.S. Cl. 200/67 G, ZOO/153 K achieve the movement of the movable Contact This [51] Illt. Cl. 01h 13/18 hammer includes a first portion engaging the movable [58] Fleld 0f Search ZOO/67 G, 68, 153 K contact on one side or the other of the pivot axis of the ZOO/6 6 67 67 H movable contact. The hammer includes striking portions on opposite sides of the first portion with the [56] References Cited striking portions alternately engaging oppositely ex- UNITED STATES PATENTS tending sections of the movable contact. A ridge is de- 3,591,747 7/1971 Dennison zoo 153 K fined at the pivot axis of the movable Contact. and the 3,535,478 l0/l970 Lewis 200/67 G first portion of the hammer is initially forced against 2,757,252 7/1956 Sparr et al.

200/67 G this ridge during switch actuation and thereafter the 3,491,2l8 1/1970 Robbins 200/68 fi portion moves rapidly over the ridge at the Same FOREIGN P E OR APPLICATIONS time as a striking portion of the hammer engages the 1,452,738 8/1966 France 200/67 G movable 10 Claims, 5 Drawing Figures R2 1 a 70 X La 4a o a 0 I 7 7 6 0 3g x 2 15 i I 11. a 1 I PAIENIED JUL 1 1191s saw 1 0F 2 HAMMER OPERATED SWITCH CONSTRUCTION This invention relates to a switch construction of the type including stationary contacts mounted on a base, and a movable contact which pivots between positions of engagement with the stationary contacts. The invention is particularly directed to a switch construction which includes a hammer element incorporated in the construction in a manner such that highly reliable operation of the movable contact can be achieved Some of the greatest problems in circuit applications come about because of switches which have a tendency to tease. Teasing involves the breaking of relatively movable contacts accompanied by a period of hesitation before these contacts become physically separated to a substantial degree. For example, in some manually operated switches, an operator may have slowly moved the actuating button or handle to cause only a slight separation of the contacts for a significant period of time during which arcing can occur. This can damage switches and also cause other circuit complications such as spurious signals particularly if the actuating means is released before switching occurs.

Various mechanical arrangements have been proposed in an attempt to prevent teasing. Some arrangements involve the use of over-center springs. These arrangements can be very effective from a performance standpoint; however, it has been found that manufacturing difficulties prevent production on a consistent economical basis. Thus, assembly operations can be very complicated, particularly where very small switches are involved. In addition, it is difficult to obtain springs which are consistently of suitable properties whereby proper performance of the switches can be expected.

It is a general object of this invention to provide an improved switch construction which includes means for preventing teasing of the switches while also provid ing a highly reliable switch operation.

It is a more particular object of this invention to provide a switch construction which includes an overcenter principal while also utilizing a hammer structure which operates in the course of switch actuation to insure rapid breaking and making of contacts without the possibility of teasing.

It is a still further object of this invention to provide a switch construction of the type described which includes a contact wiping arrangement so that the switch contacts will remain uncontaminated for reliable operation.

These and other objects of this invention will appear hereinafter and for purposes of illustration, but not of limitation, specific embodiments of the invention are shown in the accompanying drawings in which:

FIG. 1 is a vertical, sectional view, partly cut away, of a switch construction characterized by the features of this invention;

FIG. 2 is a vertical, sectional view, partly cut away, of the switch construction as it appears at an intermediate stage of operation;

FIG. 3 is a fragmentary horizontal sectional view illustrating the pivot location of the movable contact member of the structure;

FIG. 4 is a vertical, sectional view, partly cut away, of an alternative switch construction characterized by the features of this invention; and,

FIG. 5 is a vertical, sectional view, partly cut away, of an additional alternative form of the invention.

The switch construction of the invention generally comprises a base having at least a pair of stationary contacts and a pivotally mounted contact which is movable relative to the stationary contacts. A hammer is positioned on the movable contact, and drive means are provided for bringing the striking portion of the hammer into engagement with the movable contact.

The hammer consists of a first portion which is pivotally mounted relative to the movable contact and which engages the movable contact adjacent the pivot axis of the movable contact. The striking portions of the hammer extend outwardly in opposite directions from the first portion. These striking portions are thus located adjacent oppositely extending sections of the movable contact.

The movable contact defines a ridge at the pivot axis, and the first portion of the hammer is located on one side or the other of this ridge. During a switching operation, the ridge initially resists movement of the hammer. This causes pressure to be exerted on the movable contact for purposes of maintaining contact engagement in the initial stages of switch actuation. When a specific point is reached in the course of movement of the drive means, it may be referredto as the overcenter point, the hammer will be driven rapidly into engagement with the contact, this striking action serving to rapidly pivot the contact from one switch position to another. At the same time, the drive means operates on the hammer to force the first portion of the hammer beyond the ridge and over to the other side of the pivot axis of the movable contact. This action sets the switch for the next actuation, and guarantees that the switch will be tease-proof during this next actuation.

FIGS. 1 and 2 of the drawings illustrate a switch 10 which includes a horizontally disposed base 12 defining upstanding end walls 14.

Three stationary contacts 18, 20 and 22 are located on the base 12. Terminals 24, 26 and 28, respectively, are provided for these contacts.

A movable see-saw 30 is provided with contacts 32 and 34 for engagement with the outer contacts 18 and 22. The central portion 36 of the see-saw engages the contact 20 with the pivot axis for the see-saw being defined by the portion 36. As best shown in FIG. 3, extensions 38 are provided at the center of the see-saw, and these extensions are located between posts 40whereby the see-saw is confined against lateral movement.

A hammer 42 is mounted on the see-saw, and this hammer includes a first portion 44 pivotally engaging the see-saw. Oppositely extending arms 46 of the hammer provide striking portions for alternately engaging the upper surface of the see-saw on opposite sides of the pivot axis.

A drive means for the hammer includes a piston 48 pivotally connected to the hammer by means of a pin 50. This pin is journalled between side walls 52 of the hammer with the channel defined between the side walls providing an opening for receiving the end of the piston.

The piston 48 is slideable within the bore 54 defined by flipper structure 56. A spring 57 is received within bore 59 defined by the piston, and this spring serves to normally force the piston outwardly in the direction of the hammer 42. This flipper structure is located within the space 58 formed in the body of rocker element 60. The flipper includes a narrow end portion 62 which is received within a groove 64 defined in the wall of the opening 58.

The side walls of the opening 58 are spaced apart a distance greater than the width of the flipper 56 whereby the flipper has a degree of pivotal movement within the opening. Shoulder portions 66 are defined by the flipper, and these shoulder portions alternately engage the walls of the opening 58 depending upon the switch position at any given time. Shoulders 68 are formed in the end walls 14 for engaging the corners 76 of the rocker 60 to thereby limit the pivotal movement of the rocker. The rocker is provided with outwardly extending trunnion members 72 which are received in openings 74 defined by side walls 75 to thereby provide for pivotal mounting of the rocker. The side walls may extend upwardly a sufficient distance to encompass the openings or a suitable means may overlie the upper edge of the walls to confine the trunnion members.

In considering the operation of the construction illustrated, it should be noted that the switch is shown in a position of rest in FIG. 1. To actuate the switch, the operator will engage the surface 76 and push downwardly for pivoting the rocker 60 from the position shown to the opposite position shown in dotted lines in FIG. 3. It will be appreciated that either manual or mechanical operation of the rocker is contemplated. In addition, the features of the invention are adaptable to other types of actuating means, for example, a lever or paddle actuator as in toggle switches or a slide actuator.

When the rocker 60 is pivoted, the elements comprising the flipper 56, piston 48 and hammer 42 all shift positions for purposes of moving the contact 30 to the position shown in FIG. 2. Specifically, the flipper swings into a position for engagement with the opposite wall of the opening 58, and the piston 48 is carried along with the flipper. The hammer 42 moves so that the opposite striker portion 46 engages the contact as shown in dotted lines in FIG. 2 while the portion 44 of the hammer moves to the opposite side of the pivot axis of the contact 30.

The operating characteristics of the switch can be best determined by considering FIG. 2. In the rest position, the contact 34 on movable contact 30 engages stationary contact 22. One striking portion on the hammer bears against the contact, and this relationship is maintained due to the action of the spring loaded piston 48 on the hammer. When the rocker 60 is pivoted by engagement of the surface 78, the spring 57 is initially compressed since the initial pivoting action of the rocker shortens the distance between the end portion 62 of the flipper and the pin 50. This action tends to increase the pressure between the contacts, and it will be noted that this pressure will be maintained as long as the portion 44 of the hammer remains on the same side of the pivot axis of the contact 30.

As the pivoting of the rocker continues, the center line of the pin 50 eventually crosses the vertical line extending from the point of contact between the portion 44 of the hammer and the contact 30. The illustration in FIG. 2 shows the switch in a condition just prior to passage of the pin beyond this line, and it will be noted that in this condition, the contacts 34 and 22 are still pressed together.

It is important that the point of contact between the portion 44 of the hammer and the contact 30 be maintained at the side of the pivot axis of the contact. For this reason, the switch constructions of the invention include a ridge which is positioned at the pivot axis of the contact. A dwelling place for the portion 44 is provided on either side of this ridge, and the ridge resists movement of the portion beyond this dwelling place during initial switch actuation.

When the pin 50 passes the aforesaid vertical line, however, the switch operation is such that the portion 44 will be driven over the ridge. This action is accomplished along with the striking action of the hammer against the contact which is to make with a stationary contact. In the illustration of FIG. 2, the hammer will drive the contact 32 into engagement with the contact 18 if the actuating movement continues so that the pin 50 moves beyond the vertical line. The connection between the piston 48 and the hammer also accomplishes the movement of the first portion of the hammer over the ridge since the alignment of forces is such that this will occur. If, for any reason, pivoting movement of the rocker is discontinued at any intermediate point, the switch actuation will not occur, and the elements will return to a proper rest position. The particular structure illustrated is maintained free of teasing because of the relationship of the parts described.

All of the structures illustrated also provide wiping" characteristics. This action develops since the drive means comprising the flipper 56 and piston 48 forces the hammer 42 against movable contact 30 in a manner such that there is relative sliding movement between contact surfaces during each actuation of the switch.

The relative sliding movement is possible because of the clearance which is provided between the extensions 38 and the posts 40 as illustrated in FIG. 3. Because of this clearance, shifting movement of the movable contact relative to the posts is permitted. Referring to the condition of the switch shown in FIG. 1, when the rocker 60 is actuated, the initial movement of the hammer 42 causes the portion 44 to move against the ridge 80. This serves to drive the movable contact from left to right, and this movement is accomplished before the contacts move from the position illustrated. This results in wiping of the contact surfaces which substantially eliminates the possibility of contamination developing on these surfaces. Sliding movement of the contacts in the opposite direction will result when the switch is again actuated. FIG. 2 illustrates the condition of the switch immediately after the wiping action has taken I place and prior to the making and breaking of the contacts.

FIG. 4 illustrates an alternative switch construction comprising a supporting base 112 and upstanding end walls 114. The stationary contacts'll8, and 122 are positioned for engagement by movable contact 130.

The hammer structure 142 in this instance includes a cylindrical head portion 144 which fits within a correspondingly shaped recess in piston 148. This piston is movable within the bore defined by flipper 152. A spring 154 normally urges the piston outwardly to thereby provide pressure by the hammer against the movable contact. The rocker defines the open area 164 for receiving the flipper.

The operation of the switch shown in FIG. 4 is substantially the same as that of the previously described switch. Thus, the hammer 142 includes an intermediate portion 164 which is alternately positioned on opposite sides of ridge I66. Upon movement of the actuating rocker, the hammer portion 144 initially engages the ridge for purposes of achieving wiping action. As movement of the rocker continues, the flipper structure causes the hammer to drive against the movable contact while at the same time, the hammer portion 164 moves across the ridge.

in the embodiment of FIG. 5, the switch 220 is provided with a base 222 supporting stationary contacts 224, 226 and 228. Movable contact 230 is pivotally mounted on the base, and a hammer 242 is positioned on the movable contact. In this instance, the hammer defines a concave opening 244 which receives the tapered end 246 of piston 248. In this instance, the piston defines a bore 250 which recieves spring 252. The end of the spring fits around a knob 254 which is formed on the upper wall 256 of the chamber 258 defined by rocker 260. It will be appreciated that with this arrangement, the piston and flipper structures are combined into a single element.

Upon actuation of the rocker, the switch movements are essentially as previously described. Thus, the piston and flipper structure first operates to force the movable contact in sliding engagement with the stationary contacts to accomplish wiping. The making and breaking action of the switch follows in the same manner with any teasing being avoided primarily because of the relationship between the hammer and ridge structure. In this instance, the hammer defines a tapered end portion 262 which is alternately positioned on opposite sides of a ridge 264.

The structural arrangements illustrated in FIGS. 4 and 5 provide certain advantages from an assembly standpoint when compared with the structure illustrated in FIGS. 1 and 2. In FIGS. 4 and 5, there is no need to include a connecting pin between the piston and hammer structure. The structure of FIG. 5 is also more easily assembled since the flipper and piston structure comprise only one element.

In the illustrated embodiments, the movable contact members include outer contact portions which alternately engage stationary contacts while the center portion of each movable contact is continuously in engagement with a third stationary contact which comprises a common contact. It will be appreciated, however, that a variety of contact arrangements may be employed with the switch constructions illustrated. For example, one or more of the outer stationary contacts may be replaced by a pair of spaced apart contacts. In this instance, the movable contact will serve to bridge the pair of spaced contacts, and the common contact can then be eliminated. The movable contacts illustrated may be replaced by structures having a plurality of contact fingers to acheive redundancy, or the movable contact structure may comprise an assembly of independent contacts whereby separate circuits will be affected during the switching operation.

In all embodiments, a strong firing and cocking relationship exists. Thus, the operation ofthe hammer, which results in a rapid and solid making of contacts, can never occur without cocking of the switch in preparation for the next firing. The provision of the ridge 80 is particularly critical from the standpoint of insuring that firing will not occur until the elements are in position so that the switch will cock for the return movement. There is no teasing wherein contact is broken and then remade as is typical of switches where the teasing problem has not been solved. The elimination of that problem along with the provision of automatic cocking is an important feature of the invention.

It will be understood that various changes and modifications may be made in the above described construction which provide the characteristics thereof particularly as defined in the following claims.

That which is claimed is:

1. In a switch construction including a base, at least a pair of stationary contacts associated with the base, and at least one additional contact movable relative to the stationary contacts whereby the movable contact can be brought into and out of bridging relationship ,with the stationary contacts, said movable contact comprising an elongated member pivotally supported on said base, the improvement in means for controlling the movement of the stationary contact comprising a hammer positioned on said movable contact, said hammer including a first portion engaging said movable contact adjacent the pivot axis of the movable contact, and striking portions on said hammer located on opposite sides of said first portion, drive means including means for .moving the striking portions of the hammer into engagement with the movable contact for thereby changing the position of the movable contact relative to the stationary contacts, a ridge defined by said movable contact at the pivot axis location, and first and second seats defined on opposite sides of said ridge for supporting said first portion of said hammer, said drive means also including means operating to shift said first portion of said hammer from a first seat on one side of the contact member pivot axis to the second seat, said first portion of said hammer engaging said ridge when supported by a seat whereby said ridge initially resists changing of the position of said first portion, said first portion moving over said ridge substantially simultaneously with movement of the stroking portions of the hammer into engagement with said movable contacts.

2. A construction in accordance with claim 1 including extensions defined by said movable contact, means defined by said base receiving said extensions and thereby confining said movable contact, said receiving means being dimensioned to be slightly larger than the size of said extensions whereby said movable contact is free to shift relative to the stationary contacts during operation of the switch.

3. A construction in accordance with claim I wherein said drive means includes a spring loaded piston pivotally movable relative to said hammer, the force. supplied by said piston against said hammer acting to retain said movable contact in position-relative to said stationary contacts, actuation of the switch operating to force said first portion of said hammer into engagement with said ridge, said spring loaded piston being adapted to yield on continued operation of the switch to permit movement of said first portion over said ridge.

4. A construction in accordance with claim 3' including flipper means associated with said piston, and an actuating rocker for the switch, said rocker defining a hollow chamber for receiving said flipper means and piston, the dimensions of said chamber exceeding those of the chamber whereby relative movement of the flipper within the chamber can be accomplished.

5. A construction in accordance with claim 4 wherein said piston is movable within a bore defined by said flipper, said spring being positioned within said bore for urging said piston outwardly in the direction of said contact.

6. A construction in accordance with claim 4 wherein said flipper means comprises a main body portion and an integrally formed tapered end portion for engagement with said hammer, and a spring normally urging said flipper toward said hammer.

7. A construction in accordance with claim 4 including a pin interconnecting the end of said piston and said hammer whereby a fixed pivot axis between said piston and hammer is provided.

8. A construction in accordance with claim 4 wherein said hammer and piston define mating curved surfaces common terminal for the switch construction. 

1. In a switch construction including a base, at least a pair of stationary contacts associated with the base, and at least one additional contact movable relative to the stationary contacts whereby the movable contact can be brought into and out of bridging relationship with the stationary contacts, said movable contact comprising an elongated member pivotally supported on said base, the improvement in means for controlling the movement of the stationary contact comprising a hammer positioned on said movable contact, said hammer including a first portion engaging said movable contact adjacent the pivot axis of the movable contact, and striking portions on said hammer located on opposite sides of said first portion, drive means including means for moving the striking portions of the hammer into engagement with the movable contact for thereby changing the position of the movable contact relative to the stationary contacts, a ridge defined by said movable contact At the pivot axis location, and first and second seats defined on opposite sides of said ridge for supporting said first portion of said hammer, said drive means also including means operating to shift said first portion of said hammer from a first seat on one side of the contact member pivot axis to the second seat, said first portion of said hammer engaging said ridge when supported by a seat whereby said ridge initially resists changing of the position of said first portion, said first portion moving over said ridge substantially simultaneously with movement of the stroking portions of the hammer into engagement with said movable contacts.
 2. A construction in accordance with claim 1 including extensions defined by said movable contact, means defined by said base receiving said extensions and thereby confining said movable contact, said receiving means being dimensioned to be slightly larger than the size of said extensions whereby said movable contact is free to shift relative to the stationary contacts during operation of the switch.
 3. A construction in accordance with claim 1 wherein said drive means includes a spring loaded piston pivotally movable relative to said hammer, the force supplied by said piston against said hammer acting to retain said movable contact in position relative to said stationary contacts, actuation of the switch operating to force said first portion of said hammer into engagement with said ridge, said spring loaded piston being adapted to yield on continued operation of the switch to permit movement of said first portion over said ridge.
 4. A construction in accordance with claim 3 including flipper means associated with said piston, and an actuating rocker for the switch, said rocker defining a hollow chamber for receiving said flipper means and piston, the dimensions of said chamber exceeding those of the chamber whereby relative movement of the flipper within the chamber can be accomplished.
 5. A construction in accordance with claim 4 wherein said piston is movable within a bore defined by said flipper, said spring being positioned within said bore for urging said piston outwardly in the direction of said contact.
 6. A construction in accordance with claim 4 wherein said flipper means comprises a main body portion and an integrally formed tapered end portion for engagement with said hammer, and a spring normally urging said flipper toward said hammer.
 7. A construction in accordance with claim 4 including a pin interconnecting the end of said piston and said hammer whereby a fixed pivot axis between said piston and hammer is provided.
 8. A construction in accordance with claim 4 wherein said hammer and piston define mating curved surfaces in engagement with each other, said surfaces being maintained in engagement during relative movement between the piston and the hammer.
 9. A construction in accordance with claim 6 wherein said hammer defines a recess for receiving said end of said flipper, said end being pivotally movable within said recess.
 10. A construction in accordance with claim 1 wherein said stationary contacts comprise a central contact, the central portion of said movable contact bearing against said stationary contact to provide a common terminal for the switch construction. 